1. Field of the Invention
The present invention relates to a high-performance tire for a motor vehicle.
2. Description of the Related Art
British Patent Document No. GB 1,212,795 discloses a radial tire having a tread provided with a central circumferential groove, two circumferential side grooves, one on each side of the central groove, disposed substantially equidistantly between the central groove and the edges of the tread, and transverse grooves extending from opposite side of the central groove toward, but not as far as, one of the side grooves.
In said tread, the circumferential side grooves are flanked on both sides by circumferential ribs.
The invention disclosed by this document has the aim of reducing the stiffness of the tread.
U.S. Pat. No. 4,446,901 discloses a heavy-duty pneumatic radial tire comprising a carcass of a substantially radial construction composed of at least one rubberized ply layer containing cords embedded therein and a belt superimposed about said carcass for stiff reinforcement beneath a tread and composed of at least two rubberized ply layers each containing metal cords embedded therein, said metal cords of which being crossed with each other at a relatively small angle with respect to the circumferential direction of the tire, and said tread being provided with a plurality of continuous or discontinuous zigzag circumferential ribs defined along the widthwise direction of the tire by at least three substantially zigzag main grooves extending circumferentially of said tread, said main grooves comprising one or a pair of central circumferential grooves located at a substantially central region of said tread and a pair of outside circumferential grooves defining each of the outermost ribs of said tread. In this tire, the central circumferential groove has such a symmetrical cross-sectional shape with respect to a centerline of said groove that an inclination angle of a groove wall of said groove with respect to a normal line drawn from an outer surface of said tread and passing an edge of said groove in the cross-section perpendicular to said groove wall is made relatively large in a region extending from the groove bottom to at least 50% of groove depth, and the outside circumferential groove has such an unsymmetrical cross-sectional shape with respect to a centerline of said groove that an inclination angle of an outer groove wall of said groove in the rotation axial direction of the tire is made relatively large, and an inclination angle of an inner groove wall of said groove in a region extending from the outer surface of said tread to at least 10% of groove depth is made smaller than that of said outer groove wall.
U.S. Pat. No. 4,773,459 discloses a low-section tire having a tread pattern comprising 5 a plurality of main grooves substantially extending in a circumferential direction of the tire in parallel to each other and a plurality of transverse grooves intersecting the main circumferential grooves at an inclination angle also in parallel to each other, said transverse grooves are formed in upwardly-sloping, raised-bottom fashion along a longitudinal direction thereof between two main grooves, bottoms of said transverse grooves are raised in a substantially equilateral-triangle shape in cross-section in such a way that a depth of said transverse grooves is shallowest at substantially the middle portion of each transverse groove and the deepest at the bottom of said main circumferential groove.